Hey Alex,

Thanks for the response. This is the AWS scenario where there's a 1:1 NAT from the public to private IP.

I've got as far as figuring out how to advertise the public IP. But, when I forward the request to another node inside the cluster, I assume I want to double-RR that request so that my internal SIP application sees the private IP of the instance. Similarly, for outbound traffic, I want to double-RR so the remote party sees the public IP of the host.

That's the part I'm struggling with.

Best, Colin

On Sat, Jun 25, 2016 at 6:12 PM Alex Balashov abalashov@evaristesys.com wrote:

Is this the AWS NAT scenario where the public IP is actually not homed on the host itself, or are you asking about a genuine two-interface scenario?

Either way, look up the "advertise" option to the "listen" core configuration directive.

-- Alex

-- Principal, Evariste Systems LLC (www.evaristesys.com)

Sent from my Google Nexus.

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SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

Thanks for the quick reply!

Binding to two SIP ports isn't out of the question (though I'd like to avoid it if possible).

However, with this approach, I assume somewhere I must have to instruct Kamailio which outbound interface to use (i.e. tell it to use 5080 for forwarded requests to internal hosts and 5060 for requests headed out?) How else would it know to cross over the interfaces?

Best, Colin

On Sat, Jun 25, 2016 at 6:43 PM Alex Balashov abalashov@evaristesys.com wrote:

Understood. I went through this a while back.

As long as you're willing to bind to two different SIP ports (i.e. different SIP port on your internal signalling), this is the solution:

listen=udp:private.ip:5060 advertise public.ip:5060 listen=udp:private.ip:5080

Combine with enable_double_rr, shake well, et voila! :-)

-- Alex

-- Principal, Evariste Systems LLC (www.evaristesys.com)

Sent from my Google Nexus.

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SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

Awesome, thank you.

If I were to try to avoid opening another point, would it be sensible to call record_route_advertised_address() with the advertised address twice manually (once for the inbound and outbound legs with the appropriate IPs for each)? Internally I assume Kamailio's loose_route() would consume both of those on subsequent messages since they'd both be aliases for the local machine.

Would that strategy be somewhat sensible as well?

Best, Colin

On Sat, Jun 25, 2016 at 6:54 PM Alex Balashov abalashov@evaristesys.com wrote:

Yep, you'll probably have to educate it as to which outbound interface to choose, since they're on the same subnet (otherwise mhomed=1 would do the trick).

That's what the (writable) $fs pseudovar is for.

-- Alex

-- Principal, Evariste Systems LLC (www.evaristesys.com)

Sent from my Google Nexus.

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SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

Alright, I'll give both approaches a shot and see what comes up.

Thanks for the fast response time, Alex!

Best, Colin

On Sat, Jun 25, 2016 at 7:07 PM Alex Balashov abalashov@evaristesys.com wrote:

It can work, but it's more trouble than the other approach, which is essentially automagic.

-- Alex

-- Principal, Evariste Systems LLC (www.evaristesys.com)

Sent from my Google Nexus.

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SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users